Apparatus for producing carbon black

ABSTRACT

A carbon black reactor adapted for producing fine control of the &#39;&#39;&#39;&#39;structure&#39;&#39;&#39;&#39; of the carbon black produced thereby by controlling the amount of axial gas which is fed with the hydrocarbon feedstock into the reaction zone of the reactor. In one embodiment, a controlled amount of process air is admitted into an annular conduit surrounding the feedstock inlet pipe through fine adjustment of the rotational position of an apertured surrounding sleeve. In another embodiment, a control valve adjusts the amount of axial air which is admitted with the feedstock.

United States Patent Hinson, Jr.

[4 Mar. 14, 1972 [54] APPARATUS FOR PRODUCING CARBON BLACK [72]Inventor: Fletcher A. Hinson, Jr., Portland, Tex.

[73] Assignee: Ashland Oil & Refining Company,

Houston, Tex.

[22] Filed: Aug. 5, 1969 [21] Appl. No.: 847,680

[52] US. Cl ..23/259.5, 23/2094 [51] Int. Cl ..C09c 1/50 [58] Field ofSearch ..23/209.4, 209.6, 259.5; 260/679 [56] References Cited UNITEDSTATES PATENTS 2,121,463 6/1938 Wisdom ..23/209.4

3,057,688 10/1962 Williams.... ...23/209.4

3,060,003 10/1962 Williams ..23/209.4

3,211,532 10/1965 Henderson ..23/259.5 3,222,131 12/1965 Powell et al...23/209.4 3,390,960 7/ 1968 Forseth ..23/209.4 3,501,274 3/1970 Whittleet a1. ..23/259.5

Primary ExaminerEdward J. Meros Attorney-Walter H. Schneider [57]ABSTRACT A carbon black reactor adapted for producing fine control ofthe structure of the carbon black produced thereby by controlling theamount of axial gas which is fed with the hydrocarbon feedstock into thereaction zone of the reactor. In one embodiment, a controlled amount ofprocess air is admitted into an annular conduit surrounding thefeedstock inlet pipe through fine adjustment of the rotational positionof an apertured surrounding sleeve. In another embodiment, a controlvalve adjusts the amount of axial air which is admitted with thefeedstock.

3 Claims, 6 Drawing Figures PATENTEDMAR 14 1972 3, 649 207 sum 2 UF 4INVENTOR Fleicher A. Hinson, Jr.

BY fida ATTORNEY PATENTEDHAR 14 I972 SHEET H []F 4 ATTORNEY APPARATUSFOR PRODUCING CARBON BLACK BACKGROUND OF THE INVENTION The preparationof furnace-type carbon blacks by the thermal decomposition ofhydrocarbons is well known. In general, this method of preparationcomprises decomposing a hydrocarbon feedstock by the heat generated fromthe buming of a portion of the feedstock and/or by subjecting it to heatgenerated by the combustion of a hydrocarbon fuel. By controlling thereaction conditions, e.g., rates, time, temperature, and the like, it ispossible to produce various grades of furnace blacks classifiedaccording to particle size and surface area. Other physical propertiesof carbon black, however, particularly the property of structure for anyparticular grade, have been dependent, to a great extent, on feedstockcomposition. Thus, it has long been recognized that the degree ofstructure of carbon black generally increases as the feedstock fromwhich it is produced increases in molecular weight, the higher structureblacks being produced from the higher molecular weight aromatic tar andtarry residues.

By the term structure as used throughout the specification and claimshereof is meant the degree of that phenomenon to which carbon blackparticles are associated or clustered to form chainlike, or rodlike,units of varying lengths and geometric configurations. Such formationsmay occur by virtue of the physical union of numerous particles and/orby virtue of the attractive forces between and among particles. In termsof the former, a minimum or low structure carbon black is accompanied bya minimum of physical union or twinning of particles with a substantialproportion of the particles discretely divorced each from all theothers. As the degree of structure increases, an increase in the numberof rodlike carbon black units as well as an increase in the length ofsuch units is evidenced. In terms of the latter, a minimum or lowstructure results when the attractive forces between and among thecarbon black particles decrease in magnitude below the point ofinterference. As these attractive forces increase, the degree ofstructure increases as a result of interferences between and amongparticles.

Since the structure of carbon black, and in turn the modulus of carbonblack rubber compounds formed therewith, are so closely related tofeedstock characteristics, it has long been the practice in order tomodify structure without any form of aftertreatment of the carbon black,to replace one feedstock with another. The disadvantages to thispractice are apparent. In the first place, obtaining a preselectedstructure by such a method is strictly a trial and error procedure.Secondly, the capacity to accurately maintain a preselected structure,once it has been obtained, is necessarily dependent on a continuedsource of supply of the selected feedstock composition. Conversely, anydesired change of structure of the carbon black produced requires areplacement of the feedstock. In addition to these factors, moreover, isthe more important fact that any structure variation obtained byfeedstock replacement is marginal at best and is usually accompanied byan efi'ect, often adverse, on other properties of the carbon blackrubber compound, notably tensile strength and/or abrasion resistance.

Because structure of carbon black is one of the several features whichcombine to make carbon blacks unique in the area of particulate solidmatter, considerable effort has been spent in recent years in trying tocontrol the structure of any given grade of carbon black produced fromany given feedstock. In this respect, it has been recently discoveredthat any one of several techniques, when applied to the incompletecombustion furnace process, may be employed to modify structure atvarious fineness levels. A particularly effective technique fordepressing structure involves decomposition of a feedstock in thepresence of any of various extraneous additives as described, forexample, in US. Pat. Nos. 3,010,794 and 3,010,795.

In Powell et al., US. Pat. No. 3,222,131, there is disclosed a processfor the production of carbon black which discloses the control ofstructure by variations in the feedstock spray angle.

This manner of controlling carbon black structure has proved to beextremely effective, and it has the advantage of being able to produceboth increases and decreases in structure level. More specifically,where the feedstock spray is established at a very narrow includedangle, a relatively low value of structure is obtained whereas, with alarge included angle in the spray pattern, there is relatively greaterdevelopment of structure in the carbon black.

In carrying out the process of the above-mentioned Powell et al. patent,variation of the feedstock spray angle has been carried out primarily byusing various types of spray nozzles in the feedstock injector, each ofwhich is constructed to have a configuration which produces apredetermined included angle in the feedstock spray. Apparatus of thissort is eminently satisfactory for producing significantly differentvalues of the spray angle, but is not particularly suited for makingfine adjustments in structure, especially where such adjustments must bemade frequently or continuously. The ability to make such fineadjustments is of considerable commercial significance, however, and maybe necessary, for example, when variations in ambient atmosphericconditions occur suddenly and affect pressures, for example, in thevarious feedlines for fuel, feedstock and air to the carbon blackreactor. Many of the uses to which carbon black is now put require thatthe structure be very precisely controlled, and it therefore becomesquite necessary to provide for an almost vemierlike control ofstructure, which control should be capable of being exercised without,of course, shutting down the reactor.

SUMMARY OF THE INVENTION It is an object of this invention to provideapparatus for exercising very fine control over the structure of carbonblack produced in a carbon black reactor, and to enable such control tobe exercised instantly and without requiring any shutdown of the carbonblack reactor. This objective is met, according to this invention, byvarying the volume rate of the axial air or other gas which is fed,together with the feedstock flowing in the same general direction, intothe reactor. Thus, with a large volume of air being directed against theback of the feedstock spray, the spray cone is deflected inwardly andthe included angle thereof is reduced so as to produce less structure inthe resulting product. On the other hand, when the axial air volume rateis decreased, the spray angle is increased, with a resulting increase inthe development of structure.

According to one embodiment of the invention, the axial air iscontrolled by providing an aperture of variable size between the annularchamber which conveys the process air into the reactor and the pipewhich surrounds the feedstock spray line and which conveys the axialair. An adjustment external of the reactor is provided for controllingthe size of this aperture in a smoothly variable or incremental manner.In another embodiment of the invention, the axial air is provided froman air source through a control valve to the annular chamber whichsurrounds the feedstock spray line and which conveys the axial air intothe reactor so that by manipulation of the valve gradual control of theamount of axial air can be produced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectionalview of a carbon black reactor including the injector according to oneembodiment of the invention;

FIG. 2 is an enlarged longitudinal sectional view of the injectorassembly of the embodiment of FIG. 1;

FIG. 3 is a perspective view of the apparatus for controlling the axialair in the embodiment of FIGS. 1 and 2;

FIG. 4 is a longitudinal sectional view of a reactor including theinjector of an alternative embodiment of the invention;

FIG. 5 is an enlarged longitudinal sectional view of the injector of theembodiment of FIG. 4; and

FIG. 6 is a sectional view taken along the section line 66 of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1,reference numeral 1 denotes a generally tubular reactor which is dividedas shown into a first or heating zone 2, a second or reaction zone 3,and a quench zone 4 having quench ports 5. The reactor is generallysimilar in construction and operation to that disclosed in the WilliamsU.S. Pat. No. 3,060,003, the disclosure of which is incorporated hereinby reference. As illustrated, the quench zone constitutes merely anextension of the reaction zone and is of substantially similarconfiguration. The heating zone, however, is of greater diameter andshorter length than the reaction zone. For optimum results, moreover, itis preferred that the diameter of the heating zone be greater than itslength, although this is not a necessary limitau'on for operation of theapparatus in accordance with the present invention.

Heating zone 2 is provided with an inlet opening 6 through whichinjector assembly 7 projects thereinto, while quench zone 4 is providedwith an outlet opening (not shown) for withdrawal of reaction products.Positioned in the inlet end of the reaction zone is a replaceable chokering 8 of a high temperature resistant refractory material having anorifice 9. The length and shape of orifice 9 may vary and will depend tosome extent upon the particular grade of carbon black to be produced.The choke ring illustrated has an orifice whose initial diameter is lessthan that of the reaction zone but which subsequently graduallyincreases until it is substantially the same as that of the reactionzone. Choke rings of uniform internal diameter may also be used. Each ofthe zones and their inlet and outlet orifices are formed by ahigh-temperature refractory insulation 11, the entire reactor in turnhaving an outer steel shell or casing 12.

As shown more fully in FIG. 2, injector assembly 7 is composed ofsubstantially concentric tubular members 13, 14, and forming passagewaysl6, l7, and 18. That portion of tubular member 13 extending into opening6 and heating zone 2 is recessed to receive a heat-resistant refractoryinsert 19, while a gas distribution plate, more fully describedhereafter, is inserted between the inner ends of members 13 and 14.

Afiixed to the end of member 15 extending into the heating zone is adeflector through the center of which passes member 15 providingpassageway 18 with communication to the heating chamber. Deflector 20 issimilar in cross-sectional configuration to member 13 and is slightlyremoved from the inner end of members 13 and 14. Thus, an accuratelydefined circumferential orifice 21 bounded by insert 19 and the gasdistribution plate, on the one side, and deflector 20, on the otherside, is formed. The width of this opening may be readily varied by asimple adjustment to the deflector which will be subsequently more fullydescribed. As are all portions of the reactor that are subjected to highcombustion and reaction temperatures, the deflector is constructed of ahigh temperature refractory material. The inner surface of the deflectorfacing circumferential orifice 21 and the gas distribution plate areboth composed of heat-resistant stainless steel. Thus, both parts may bemaintained within close dimensional tolerances.

Extending through passageway 18 is a hydrocarbon feedstock member 22having at its inner end a nozzle or injector 23. This nozzle may takeany form but is of such design as to direct the feedstock towardsorifice 9 in a vaporized or atomized form. The nozzle structures foundto be particularly satisfactory are those which produce a so-calledsolid cone spray. That is, the outline of the spray is in the form of acone having its apex at the tip of the nozzle, and the droplets in thespray are distributed throughout the cone. The included angle of thespray cone, measured in the absence of deflecting gases, will be limitedto some extent by the position of the deflector in the heating chamber,and usually will not exceed about 180.

Connected with passageway 17 is a duct 24 which supplies anoxygen-bearing gas from a suitable source, which gas is then conveyedthrough passageways 17 and through orifice 21 to the heating chamber 2.Such oxygen-bearing gas, which may be air, shall hereinafter be referredto as process air. In addition, an apertured sleeve 25 which isrotatable about tubular member 15 provides an aperture of controllablesize between passageway 17 and passageway 18 so that a controllableamount of the oxygen-bearing gas in duct 24 may be introduced intopassageway 18 and caused to issue from the open end of passageway 18adjacent the spray of feedstock issuing frorn nozzle or injector 23.Thus, the oxygen-bearing gas which flows through passageway 18,hereinafter referred to as axial air, surrounds the feedstock sprayclosely adjacent its point of origin.

Connected with passageway 16 and communicating therethrough and throughorifice 21 with the heating chamber is a means 26 for introducing fuel.Entry of fuel from passageway 16 into orifice 21 may be by any suitablemeans for injecting it in a highly vaporized or atomized form so that athorough mixing therewith of the process air will be obtained in theorifice.

The means for providing fine control of the amount of axial air admittedfrom duct 24 and passageway 17 into passageway 18 is shown in greaterdetail in FIG. 3. As shown, the inner tu bular member 15 is providedwith an elongate through slot 15a. Fitted about the member 15 at thelocation of the slot is a tubular sleeve 25 which is freely rotatableabout the member 15. As shown in FIG. 2, the left-hand end of sleeve 25extends exteriorly of the reactor through suitable gastight packingglands or the like so that an operator may readily rotate the sleeve 25about member 15 by means of handle 25a. Sleeve 25 is provided with agenerally triangularly shaped opening 25b in its sidewall, the base ofthe triangle preferably having a length which substantially correspondsto the length of the slot 150 and member 15. It will be apparent that asthe sleeve 25 is rotated about member 15, the effective size of theaperture through the two mating members can readily be adjusted in avery gradual manner so as to provide a very fine degree of control ofthe amount of axial air which is provided.

As previously described, variation in the amount of axial air makespossible an adjustment in the included angle of the feedstock spray.Although large variations in the spray angle are not obtainable throughcontrol of the axial air, it is possible to provide a very fine degreeof control so that, in eflect, a vernier adjustment of this parametermay be obtained with corresponding precise adjustments in the structureof the carbon black produced by the reactor.

In operation of the apparatus of FIGS. l-3, process air is introducedthrough duct 24 and passes through passageway 17, being injected throughthe open end thereof into circumferential orifice 21. Simultaneously, ahydrocarbon fuel is introduced through inlet 26 and passes throughpassageway 16, being injected into orifice 21 through a plurality ofcircumferentially spaced ports. As the stream of process air flowsradially outward passing the above-mentioned ports, it is at its maximumvelocity and minimum static pressure. As the vaporized or atomized fuelis injected into the stream at a controlled velocity, a thorough mixingof fuel therein is rapidly obtained. The resultant fuel-air mixtureflows radially outward following the contour of orifice 21 and isignited as it passes into the heating zone. The burning mixture and itsproducts of combustion continue the flow radially outward from the axisof the heating zone as a uniformly expanding disc towards thecircumferential surface of the heating zone. It then follows a flowpattern as shown by the arrows in FIG. 1, tending to flow parallel tosaid circumferential surface towards the opposite end of the heatingzone where it is directed radially inward toward the axis of the zoneand orifice 9.

As hydrocarbon fuel and process air are introduced into the reactor,through their respective inlets, hydrocarbon feedstock as a vapor orfinely divided liquid spray is introduced through inlet 22 to beinjected into the heating zone through nozzle 23. This injection takesthe form of an expanding cone directed towards orifice 9. Thetemperature of the feedstock is rapidly raised as it approaches orifice9 and is thoroughly mixed with and dispersed into the hot combustiongases resulting from the burning of the hydrocarbon fuel. The resultantmixture of combustion products and feedstock passes through the orificeinto the reaction zone where the cracking of the feedstock is terminatedas desired by quenching the mixture with water or other suitable coolingmedium introduced through quench ports 5. The cooled reaction gas withentrained carbon black then exits from the reactor through an outletopening, not shown, for subsequent separation and collection of carbonblack by means which form no part of this invention.

The inventive concept of this invention is applicable not only to acarbon black reactor of the type disclosed in FIGS. 1 and 2 which, asaforesaid, corresponds generally to the type of reactor disclosed in theWilliams patent 3,060,003, but is equally applicable to the type ofcarbon black reactor disclosed in the Whittle et al. application Ser.No. 678,962 filed Oct. 30, 1967 now U.S. Pat. 3,501,274. In the type ofreactor disclosed in such application, the process air is not introducedinto a passageway which immediately surrounds the conduit conveying thefeedstock and axial air to the reaction zone but is instead conveyed tothe reaction zone through an annular passageway which is defined in partby a conically shaped hood which surrounds the inner conduit conveyingthe feedstock and axial air and also the separate conduits forconveying, respectively, the fuel and air which are admixed and burnedin the heating zone.

Referring to FIG. 4, the various elements 3, 4, 5, 8, 9, 10, ll, 12, and19 are all similar to the corresponding elements shown in FIG. 1 andperform corresponding functions. The injector 30 of this embodiment isdifferent from the injector 7 of FIG. 1, and the injector of this secondembodiment is therefore shown in greater detail in FIG. 5. Thus, theinjector comprises a generally conical shell 31 having a flange 32 atone end thereof for mounting the burner on the reactor. A sleeve 33 issupported on a cylindrical extension 34 of shell 31 by means of aplurality of vanes 35. The upstream end of sleeve 33 is contoured at 36to conform to the inclination of conical shell 31 thereby to provide acircular space acting as a combustion supporting gas inlet. As a resultof this gas inlet configuration, tees of the type shown at 24 in FIG. 1are avoided, and lower combustion supporting gas pressure drops areachieved.

The downstream end of shell extension 34 is attached, e.g., by welding,to the upstream end of a forged header member 37. The outermost surfaceof header member 37 is smoothly curved, as illustrated, and a flaredflange 38 having a curvature smoothly continuing that of header member37 is attached, e.g., by welding, to the downstream end of header member37. Flared flange 38 acts as the interior surface of a deflectorstructure generally similar in operation to that of deflector 20described earlier. To this effect, a cast refractory material body 39 isattached to flange 38 with the aid of a plurality of stainless steelclips generally designated 40 which are welded to the flange 38.

The downstream end of a sleeve 33 is provided with a ring 41 having aninterior curvature generally conforming to the curvatures of flange 38and of forged header member 37. Members 37, 38 and 41 thus cooperatewith one another to provide a smooth streamlined continuation of thepassageway for combustion supporting gas, terminating in an angular orring-shaped orifice 42.

Forged header member 37 is provided with a central bore extending alongthe axis of the burner which is threaded at 43 for reception of anelongated pipe 44 through which the feed stock supply conduit 45 maypass. Pipe 44 provides a conduit for conveying axial air to be mixedwith the feedstock, with the amount of axial air being controlled by thedegree of opening of a valve 46 connected in pipe 44. Cast refractorymember 39 is also supplied with a central bore 47 mating with andcomprising a continuation of the bore which is threaded at 43 forreception of the feedstock supply nozzle. Header member 37 has a pair ofinterior chambers 48 and 49 for reception of atomizing air (when it isused) and a hydrocarbon fuel respectively. An air inlet pipe 50 isattached to the header member 37, and a fuel pipe 51 is also attached tosaid header member, with each of said pipes 50 and 51 being suppliedwith appropriate screw couplings 52 for attachment to the appropriatesources of air and fuel.

The arrangement of FIG. 5 operates, in general, in the manner previouslydescribed in reference to FIGS. 1 and 2, but unifies the deflector andburner proper, and simultaneously provides an improved arrangement offlow passages for combustion supporting gas, fuel, and atomizing air(when desired). While the arrangement of FIG. 3, as described, permitseither liquid or gaseous fuels to be employed, it will be understood, ofcourse, that similar provision may be made in the arrangement of FIG. 1.

In the embodiment of FIGS. 4 and 5, axial air is conducted from asuitable source of air or other oxygen-bearing gas (not shown) throughvalve 46 and through pipe 44 to be mixed with the feedstock which isadmitted through the feedstock inlet pipe 45. Fine control over theincluded angle of the feedstock spray may be obtained by adjusting theamount of axial air provided in accordance with the degree of opening ofvalve 46, thereby making possible fine adjustment of the structure ofthe carbon black produced.

Other combustible and noncombustible gases may be used in addition to orin place of the axial air for van'ably deflecting the feedstock spray tonarrowed included angles and thereby controlling the structure of theblack in accordance with the invention. For instance, the use of steamand/or natural gas and/or reactor tail gas and/or nitrogen and/or otherinert gas is suggested. Such other gases may be injected into a reactorequipped with a pipe 44 like that shown in the figure 4-6 embodiment ofthe invention by connecting said pipe with one or more sources of thedesired gas(es) and means for regulating the flow, where use of a gasother than air results in the delivery of a higher or lowerconcentration of oxygen to the combustion zone than would be provided bythe use of air, the rate of introduction of the main process airstrearnmay be adjusted accordingly to maintain the desired overall molar ratioof fuel and hydrocarbon feedstock relative to oxygen in the furnace.

Through the use of the present invention, fine control of structure ismaintained while holding substantially constant such other properties asparticle size, tinctorial power, surface area, ash content and the likewhich characterize a given grade of carbon black. By substantially asapplied to the constancy of such properties, it is intended to conveythat such variations as occur in each of the properties fall generallywithin the permissible ranges of variation established for a.preselected grade of carbon black, e.g., l-IAF, ISAF, SAF, SPF and thelike, which is being manufactured in the furnace. These and many othergrades of black and the pennissible ranges of variation for the variouscharacterizing properties therefor are widely recognized throughout theindustry and sanctioned by such recognized authorities as the ASTM.

What is claimed is:

l. A fumace-type carbon black reactor having a generally tubular chamberincluding a generally tubular enlarged combustion zone at the upstreamand thereof,

an axially disposed feedstock inlet adapted to discharge a feedstockinto said combustion zone adjacent its central axis,

an axially disposed gas inlet adapted to discharge a gas into saidcombustion zone, admixed with said feedstock and also generally adjacentits central axis, first means for introducing both a fuel and anoxygen-bearing gas to said combustion zone for burning therein,comprising an annular passageway surrounding said gas inlet,

means for introducing said feedstock from said feedstock inlet into saidcombustion zone in a divergingly angled spray pattern,

and means for controlling the rate of flow of gas provided by said gasinlet comprising means defining an aperture of variable size betweensaid annular passageway and said gas inlet.

cludes aperture means and further includes means extending externally ofsaid tubular chamber for rotation of said sleeve to thereby adjust thesize of the combined effective aperture through said pipe and saidsleeve.

2. The apparatus of claim 1 in which said gas inlet comprises a pipe ofcircular cross section having an aperture therein, and said aperturedefining means comprising a sleeve slidable on said pipe and so disposedthat the effective aperture through said pipe aperture is dependent upontheir relative positions.
 3. The apparatus of claim 2 in which saidsleeve also includes aperture means and further includes means extendingexternally of said tubular chamber for rotation of said sleeve tothereby adjust the size of the combined effective aperture through saidpipe and said sleeve.